CN103472409A - Sensor body and induction type three-axis magnetic field sensor applying same - Google Patents

Abstract

The invention provides a sensor body and an induction type three-axis magnetic field sensor applying the sensor body. The sensor body comprises a magnetic core structure and an induction coil, the longitudinal section of the magnetic core structure is in an I type, the middle part of the magnetic core structure is a long and thin rod-shaped magnetic core, and the two ends of the magnetic core are flat magnetic flux focusers. The induction coil is evenly wound on the periphery of the magnetic core of the magnetic core structure. Due to the fact that the magnetic flux focusers are added at the two ends of the long and thin magnetic core and used for focusing magnetic flux, the length-diameter ratio of the magnetic core is equivalently improved, and the noise limit of a traditional induction type magnetic field sensor in confined space is broken through.

Description

The induction type triaxial magnetic field sensor of sensor body and application thereof

Technical field

The present invention relates to sensor technical field, relate in particular to a kind of sensor body and apply its induction type triaxial magnetic field sensor.

Background technology

The induction type magnetic field sensor refers to the instrument of measuring the faint variation in magnetic field based on the Faradic electricity magnetic induction principle.In marine geophysics observation, be mainly used in the telluric electromagnetic sounding (MMT) and ocean controllable source electromagnetism (CSEM) instrument in the construction of Marine Sciences observational network, marine oil and gas exploration.It is one of the most extensive measurement of magnetic field instrument in marine geophysics observation.

Marine Sciences observation field, observe and study its room and time regularity of distribution of ocean earth magnetism, it is one of substance of Marine Sciences observation, high sensitivity induction type magnetic field sensor is one of indispensable instrument of these scientific activities, utilize highly sensitive induction type magnetic field sensor can accurately obtain the natural magnetic field change information of 0.1mHz-100Hz, this band information has extremely important reference value to earth science researches such as submarine geology structure, slab structure motions.

Rise along with deepwater petroleum exploration, Marine Electromagnetic Approach has become one of important means of marine oil and gas exploration, the practice of marine oil and gas exploration both at home and abroad shows: the marine electromagnetic method is by the identification of the resistivity to the target geologic body, greatly improve the drilling well success ratio, effectively reduced the cost of offshore oil drilling exploitation.The magnetic-field component of nearly all marine electromagnetic method instrument is measured and is all adopted the induction type magnetic field sensor to carry out, as the marine electromagnetic instrument of the companies such as U.S. SIO research institute, Schlumberger.

Therefore, no matter be Marine Sciences activity or ocean resources energy field, the induction type magnetic field sensor is all indispensable core technologies, is directly restricting the development of China's marine electromagnetic instrument.

For ocean magnetic field, survey, the sensitivity of induction type magnetic field sensor is 10 ^-4nT/ √ Hz-10 ^-3nT/ √ Hz (during 1Hz).Existing induction type magnetic field sensor comprises MTC-80 type, the MTC-50 type magnetic field sensor of Canadian PHOENIX Geophysics Limited, MFS-06 (e) type of German Metronix Geophysics company, MFS-07 type magnetic field sensor etc.These induction type magnetic field sensors, outward appearance is elongated cylindrical, and length is at 1m-1.4m, and about diameter 10cm, quality is generally at 8kg-12kg.During for hydrospace detection, three magnetic field sensors need to be adopted respectively to the pressure-bearing cabin sealing of elongated cylindrical, material is plastics or aluminium, and signal is passed to the receiver of ball float inside by water-proof cable.Whole instrument volume surpasses 1m ³, weight is greater than 400kg, needs 4-5 deep-sea ball float simultaneously, is used for guaranteeing enough buoyancy, and excessive volume and too high cost bring huge challenge to exploration operation.Yet, if dwindle the volume of induction type magnetic field sensor, can cause its sensitivity, equivalent input noise increases, thereby can not meet the demand of marine electromagnetic exploration.

Summary of the invention

(1) technical matters that will solve

In view of above-mentioned technical matters, the invention provides a kind of sensor body and apply its induction type triaxial magnetic field sensor, to realize the miniaturization of induction type triaxial magnetic field sensor under the prerequisite guaranteeing measuring accuracy.

(2) technical scheme

According to an aspect of the present invention, provide a kind of sensor body.This sensor body comprises: core structure, and longitudinal profile is I shape, and center section is slender rod shaped magnetic core, and two end portions is flat focus magnetic flux device; Inductive coil, uniform winding is in the periphery of core structure magnetic core.

According to an aspect of the present invention, also provide a kind of induction type triaxial magnetic field sensor.This induction type triaxial magnetic field sensor comprises: the sensor body module comprises detection direction three sensor body as above perpendicular to each other; Three groups of chopper amplification circuit, carry out the amplitude enhancing to the signal of three sensor body inductive coil outputs by chopping way respectively.

(3) beneficial effect

From technique scheme, can find out, sensor body of the present invention and the induction type triaxial magnetic field sensor of applying it have following beneficial effect:

(1) assemble magnetic flux by add disk at original slender type magnetic core two ends, the raising of equivalence the length-diameter ratio of magnetic core, broken through the noise margin of traditional induction type magnetic field sensor in the finite space;

(2) by the signal compensation module, make three axis signal crosstalk signal minimums, improved the magnetic-field measurement precision, realize integrated tri-axial magnetic field sensor in the finite space.

The accompanying drawing explanation

Fig. 1 is the longitudinal profile schematic diagram according to embodiment of the present invention sensor body;

Fig. 2 is the comparison diagram of sensor body shown in the Fig. 1 obtained by simulation software and conventional magnetic field sensors magnetic flux;

Fig. 3 is the structural representation according to embodiment of the present invention induction type triaxial magnetic field sensor;

Fig. 4 is the schematic diagram of sensor body module in the induction type triaxial magnetic field sensor shown in Fig. 3;

Fig. 5 is the curve that shown in Fig. 3, in the induction type triaxial magnetic field sensor, the chopper amplification circuit is expanded the sensor bandwidth;

Fig. 6 is the structural representation of chopper amplification circuit in the induction type triaxial magnetic field sensor shown in Fig. 3;

Fig. 7 is the circuit diagram of matching network module in the chopper amplification circuit shown in Fig. 6;

Fig. 8 is the circuit diagram of modulation module in the chopper amplification circuit shown in Fig. 6;

Fig. 9 is the circuit diagram of electric current amplification module in the chopper amplification circuit shown in Fig. 6;

Figure 10 is the circuit diagram of demodulation module in the chopper amplification circuit shown in Fig. 6;

Figure 11 is the circuit diagram of filtration module in the chopper amplification circuit shown in Fig. 6;

The schematic diagram that Figure 12 is embodiment of the present invention induction type triaxial magnetic field sensor frequency response measurement method.

Embodiment

For making the purpose, technical solutions and advantages of the present invention clearer, below in conjunction with specific embodiment, and, with reference to accompanying drawing, the present invention is described in more detail.It should be noted that, in accompanying drawing or instructions description, similar or identical part is all used identical figure number.The implementation that does not illustrate in accompanying drawing or describe is form known to a person of ordinary skill in the art in affiliated technical field.In addition, although this paper can provide the demonstration of the parameter that comprises particular value, should be appreciated that, parameter is without definitely equaling corresponding value, but can in acceptable error margin or design constraint, be similar to corresponding value.The direction term of mentioning in embodiment, such as " on ", D score, 'fornt', 'back', " left side ", " right side " etc., be only the direction with reference to accompanying drawing.Therefore, the direction term of use is not to be used for limiting the scope of the invention for explanation.

Sensor body of the present invention and the induction type triaxial magnetic field sensor of applying it are assembled magnetic flux by add disk at original slender type magnetic core two ends, the equivalence raising the length-diameter ratio of magnetic core, and by the signal compensation module, make three axis signal crosstalk signals be inhibited, thereby realized the miniaturization of induction type triaxial magnetic field sensor under the prerequisite that guarantees precision.

In one exemplary embodiment of the present invention, provide a kind of sensor body.Fig. 1 is the longitudinal profile schematic diagram according to embodiment of the present invention sensor body.Please refer to Fig. 1, the section of magnetic core is I shape, and center section is elongated right cylinder magnetic core, and length is 20cm, and diameter is 1.0cm, and two end portions is the flattened cylindrical shape, and length is 1.0cm, and diameter is 11cm.This three parts magnetic core is fixed together closely.

The flat right cylinder magnetic core of two end portions, be called the flux device.In sensor body of the present invention, the ratio of two end portions focus magnetic flux device diameter and center section diameter is between 2: 1～10: 1, and the ratio of the length of magnetic flux collector diameter and center section is between 1: 1～1: 5.

Sensor body core structure material all adopts soft magnetic ferrite, is preferably Ferrite Material.The initial permeability of this material is high, conductivity is low, can realize the lossless amplification of magnetic induction density, thereby reaches required sensitivity.

For the magnetic core that shape is generally arranged, without the flux device, due to the existence of demagnetizing field, magnetic core Effective permeability μ _appbe far smaller than the initial permeability of material itself.For rod core, its demagnetizing factor is:

$N=\frac{1}{m^2-1}\{\frac{m}{{2(m^2-1)}^{\frac{1}{2}}}\ln \left(\frac{m+{(m^2-1)}^{\frac{1}{2}}}{m-{(m^2-1)}^{\frac{1}{2}}}\right)-1\}---\left(1\right)$

Effective permeability is:

${\mathrm{\&mu;}}_{\mathrm{app}}=\frac{{\mathrm{\&mu;}}_{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="HDA0000381297950000042.png,HDA0000381297950000061.png"\; state="\{\{state\}\}">r</figure-callout>}}}{1+N({\mathrm{\&mu;}}_r-1)}---\left(2\right)$

Wherein, the length-diameter ratio that m is rod core,

μ _rfor the magnetic material initial permeability.

Fit tightly diameter D at the magnetic core two ends, after the magnetic flux collector of height t, the length-diameter ratio in formula (1) is effective permeability is:

${\mathrm{\&mu;}}_{\mathrm{app}}=\frac{{\mathrm{\&mu;}}_{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="HDA0000381297950000042.png,HDA0000381297950000061.png"\; state="\{\{state\}\}">r</figure-callout>}}}{1+N\&times;{\left(\frac{d}{D}\right)}^2({\mathrm{\&mu;}}_r-1)}---\left(3\right)$

Formula (1-3) is magnetic core implementation Main Basis, can arrive, and with the magnetic core of magnetic flux collector, i.e. magnetic core Effective permeability μ _appenlarge markedly.

Fig. 2 is the comparison diagram of sensor body shown in the Fig. 1 obtained by simulation software and conventional magnetic field sensors magnetic flux.As shown in Figure 4, for same magnetic core, have, without the average effective magnetic permeability of magnetic flux collector, be respectively 709 and 168, the present embodiment magnetic core has partly reached the Effective permeability identical with the magnetic core of length 1.2m.As shown in Figure 4, the magnetic flux collector has not only improved Effective permeability simultaneously, and what also make Effective permeability distribute in whole core length scope is more smooth, makes available magnetic core part more.

In the periphery of core structure, adopt engineering plastics to support as skeleton and the protection core structure, uniform winding multiturn coil on skeleton.

Multiturn coil adopts the mode of oxygen-free copper enameled wire to realize, the enameled wire diameter is at 0.1mm-0.42mm, during winding, to from left to right uniform winding one deck, then the uniform winding second layer of turning left from the right side, back and forth be wound around successively, every layer of number of turns is at the 1000-8000 circle, be wound around altogether the 10-40 layer, number of total coils is about the 10000-80000 circle, guarantees enough sensitivity.

The coil impedance size, plan as a whole to optimize in conjunction with parameters such as the noise level of subsequent conditioning circuit, input impedance and consider.In general, the noise level of circuit is certain, for this noise level, by wire circle N, wire diameter d _w, around the cylinder diameter d _coilbe made as variable etc. parameter, will be by the coil resistance R of its decision _sc, coil inductance L _pc, coil capacitance C _scbringing the noise calculation formula into etc. known parameters such as parameter and magnetic core equivalent area S is optimized.Suppose e _nwfor circuit voltage noise, i _nwfor circuital current noise, K _b=1.38 * 10 ^-23the Boltzmann constant, T _cbe absolute temperature, generally get 300K, A _corefor the magnetic core equivalent area.

Amplifier voltage noise equivalent input magnetic noise:

$b_{\mathrm{nie}}\left(f\right)=\frac{e_w}{\left|2\mathrm{\&pi;f}{\mathrm{\&mu;}}_{\mathrm{app}}\mathrm{NS}\right|}---\left(4\right)$

Amplifier current noise equivalent input magnetic noise:

$b_{\mathrm{iie}}\left(f\right)=\frac{i_w\&times;|R_{\mathrm{sc}}+\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="HDA0000381297950000061.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;f}{L}_{\mathrm{pc}}|}{\left|\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="HDA0000381297950000061.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;f}{\mathrm{\&mu;}}_{\mathrm{app}}\mathrm{NS}\right|}---\left(5\right)$

The thermonoise equivalence input magnetic noise of Coil resistance comprises enameled wire resistance and core loss:

$b_{\mathrm{rsce}}\left(f\right)=\frac{\sqrt{4K_b{T}_c{R}_{\mathrm{sc}}}}{\left|\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="HDA0000381297950000061.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;f}{\mathrm{\&mu;}}_{\mathrm{app}}\mathrm{NS}\right|}---\left(6\right)$

Suppose to ignore other small noises, the equivalence input magnetic noise that sensor is total:

$b_{\mathrm{nte}}\left(f\right)=\sqrt{{b^2}_{\mathrm{nie}}\left(f\right)+{b^2}_{\mathrm{iie}}\left(f\right)+{b^2}_{\mathrm{rsce}}\left(f\right)}---\left(7\right)$

Optimized-type (7), the coil parameter that makes equivalence input the magnetic noise minimum is the optimum of coil parameter.

In the present embodiment sensor body, by adopting the flux device, each sensor body just can realize the magnetic permeability equated with longer magnetic core with less length, equivalent raising the length-diameter ratio of magnetic core, in less volume, realized higher sensitivity.

Based on the sensor body module, in another exemplary embodiment of the present invention, also provide a kind of induction type triaxial magnetic field sensor.Fig. 3 is the structural representation according to embodiment of the present invention induction type triaxial magnetic field sensor.

Please refer to Fig. 3, the present embodiment induction type triaxial magnetic field sensor comprises: sensor body module, three groups of chopper amplification circuit and signal compensation module.Wherein, the sensor body module is the sensor body module of above-described embodiment.The signal input part of three groups of chopper amplification circuit is connected to respectively the two ends of inductive coil in the respective sensor body module.The signal input part of signal compensation module is connected to the signal output part of three groups of chopper amplification circuit.Wherein, produced respectively induced voltage signal by measuring magnetic field on three sensor body, the signal amplitude enhancing after the chopper amplification circuit respectively of these three groups of induced voltage signals, and obtained three-dimensional magnetic field information after the inhibition to three axle crosstalk signals by the signal compensation module.

Below respectively two other ingredient of the present embodiment induction type triaxial magnetic field sensor is elaborated.

1, sensor body module

Fig. 4 is the schematic diagram of sensor body module in the induction type triaxial magnetic field sensor shown in Fig. 3.Please refer to Fig. 4, this sensor body module comprises the sensor body of detection direction three above-described embodiments perpendicular to each other.Wherein, these three sensor body are respectively along x direction of principal axis, y direction of principal axis and z direction of principal axis.For fear of the three-axis sensor quadrature crosstalk, simultaneously also in order to shield outside electromagnetic interference, each sensor body all is placed in the aluminium shielding box.

Whole sensor body module cumulative volume is no more than 23cm*23cm*23cm, can directly be integrated in the ocean sealed ball float that a diameter is 17 inches, realizes the magnetic-field measurement in seabed.This sensor body module can meet ocean EM exploration and measure sensitivity, meets again quality the lightest, the minimum requirement of volume.

2, chopper amplification circuit

For three-axis sensor, for overcoming, to crosstalk, each axle sensor is furnished with a chopper amplification circuit, totally three groups of circuit.The structure of these three groups of chopper amplification circuit is identical, below with wherein one group be that example describes.

The signal input part of chopper amplification circuit is connected to the two ends of inductive coil in the sensor body module.The chopper amplification main circuit will be realized two functions: the first, expand bandwidth, for the front end inductive coil of induction type triaxial magnetic field sensor, in order to realize high sensitivity, therefore wire circle is larger, causes the resonance frequency of coil can be too not high, likely drops in bandwidth of operation.And this resonance peak can make sensor job insecurity in bandwidth of operation, cause concussion, therefore, this chopper amplification circuit adopts matching network and electric current amplification mode, the sensor bandwidth is expanded, as shown in Figure 5 simultaneously; The second, reduce 1/f noise, in low frequency amplifies, be subject to the impact of the 1/f noise of electron device own, while directly amplifying, useful signal will be flooded by noise, so the amplification of low frequency magnetic field signal need to overcome the impact of 1/f noise, just can obtain useful amplification.

As shown in Figure 6, the chopper amplification main circuit will be comprised of five modules, comprising: matching network module, modulation module, electric current amplification module, demodulation module and filtration module.Wherein, the matching network module, for inductive coil export resonance point is compensated, is expanded the bandwidth of operation of inductive coil.Modulation module is modulated to high frequency for the square-wave signal that adopts predeterminated frequency by the signal of matching network module output, thus the chopping signal of realization.The electric current amplification module adopts operational amplifier or the pipe amplifier is carried out to the low-noise current amplification to the chopping signal of modulation module output.Demodulation module adopts and the on all four circuit structure of modulation, and the useful signal in electric current amplification module output signal is demodulated to low frequency, and the 1/f noise that amplifier is introduced is modulated onto high frequency.Filtration module, the high-frequency signal that modulation /demodulation is brought filters, and retains useful signal.

2.1 matching network module

The matching network module, for inductive coil export resonance point is compensated, expand the coil working bandwidth.

The matching network module mainly adopts resistance, inductance, electric capacity series-parallel network.As shown in Figure 7, pass through the first resistance R 1 series connection ground connection from the induced signal of inductive coil output; And the induced signal of this inductive coil output after the parallel circuit of the second resistance R 2 and the first inductance L 1 as the output V of matching network module _in.Wherein, the first resistance R 1 is 25.5kOhm, and the second resistance R 2 is 10kOhm, and the first inductance L 1 is 220mH.

2.2 modulation module

Modulation module mainly adopts cmos analog switch chip ADG413 (U1) to realize, for the square-wave signal that adopts predeterminated frequency, the signal of matching network module output is modulated to high frequency, thus the chopping signal of realization.

Please refer to Fig. 8, the pin one 3 of U1 connects VCC, i.e. the positive voltage of power supply; Pin one 2 connects VL, is the logic voltage value, is 5V; The positive signal V of pin 3 and pin one 1 matching connection mixed-media network modules mixed-media output _in; Pin one, pin 8, pin 9, pin one 6 connect clock signal clk; Pin 6, pin one 4 connect signal ground; Pin two, pin one 5 are just being exported for signal, and pin 7, pin one are born for signal output for No. 0, connect respectively the input end V of amplification module _m1and V _m2.

2.3 electric current amplification module

Please refer to Fig. 9, amplification module is divided into first, second and third grade of series connection amplifying circuit.Wherein, first order amplifying circuit is for the preposition amplification of low noise, and second level amplifying circuit, for power amplification, adopts negative feedback mode to connect between first and second two-stage, form an integral body; The reversal of poles of third level amplifying circuit.

First order amplifier section forms (Q1 and Q2) (model of Q1, Q2 is INF146) by FET to pipe.Wherein: the G utmost point of Q1, Q2 is connected to respectively the output V of modulation module _m1and V _m2; The S utmost point short circuit of Q1 and Q2, its common port is connected to power supply negative voltage VSS through current source I1, and the model of I1 is J507; The D utmost point of Q1, Q2 is connected to power supply positive voltage VCC by the 3rd resistance R 3, the 4th resistance R 4 respectively, and wherein, the 3rd resistance R 3 and the 4th resistance R 4 are 3.0kOhm.The D utmost point of Q1, Q2 is respectively as the output terminal of first order amplifying circuit.

Second level amplifying circuit adopts MAX4101ESA (U2) to realize.Wherein: the pin two of U2 is connected to the D level of Q2 in first order amplifying circuit successively through the 5th resistance R 5 and the first capacitor C 1.The pin 3 of U2 is connected to the D utmost point of first order amplifying circuit Q1 successively by the 6th resistance R 6 and the second capacitor C 2.Wherein, the first capacitor C 1 and the second capacitor C 2 equate, are 100nF, and the 5th resistance R 5 and the 6th resistance R 6 equate, are 1kOhm.U2 pin 6 is connected with pin two with the 8th resistance R 8 shunt circuits through the 4th capacitor C 4, and the 4th capacitor C 4 values are 10pF, and the 8th resistance R 8 is 200kOhm.The pin 3 of U2 is connected with ground through the parallel circuit of the 7th resistance R 7 and the 3rd capacitor C 3, and the 7th resistance R 7 is 200kOhm, and the 3rd capacitor C 3 is 10pF.The pin 6 of U2 is connected with Vm1 by the 20 resistance R the 20, the 18 resistance R 18 series connection, adopts between the 18 resistance R 18 and the 20 resistance R 20 with the 19 resistance R 19 and is connected in series on the ground.The pin 4 of U2 connects power-VSS.The pin 7 of U2 connects the positive VCC of power supply.The pin 6 of U2 is as the output terminal of second level amplifying circuit.The pin 6 of U2 is connected with Vma2 by the 5th capacitor C 5, and Vma2 is connected with ground by the 12 resistance R 12.The 5th capacitor C 5 is 100nF, and the 12 resistance R 12 is 1kOhm.

Third level amplification also adopts MAX4101ESA (U3) to realize.Wherein: the pin two of U3 (input negative terminal) is connected to the pin 6 of U6 in the amplifying circuit of the second level successively through the 9th resistance R 9.The pin two of U3 (input anode) ground connection.The 9th resistance R 9 resistances are 1kOhm.Between the pin two of U3 and pin 6, adopt the tenth resistance R 10 to realize series loop, the 8th resistance R 10 is 1kOhm.The pin 4 of U3 connects power-VSS.The pin 7 of U3 connects the positive VCC of power supply.The pin 6 of U3 is connected to output terminal V by the 6th capacitor C 6 _ma1, V _ma1by the 11 resistance R 11, with ground, be connected.The 6th capacitor C 6 is 100nF, and the 11 resistance R 11 is 1kOhm.V _ma1and V _ma2input end as third level amplifying circuit.

2.4 demodulation module

Please refer to Figure 10, demodulation module and modulation module symmetry, adopt ADG413 (U4) to realize.The pin 3 and 14 of U4 accesses respectively the signal V from amplification module _ma1with signal V _ma2; The pin one of U4 and pin one 6 connect the CLK signal simultaneously; The pin 4 of U4 connects power-VSS signal; The pin 5 of U4 connects the GND signal; The pin one 2 of U4 meets VL, and pin one 3 meets the positive VCC of power supply; The pin two of U4 and pin one 5 connect respectively the 13 resistance R 13 and the rear short circuit of the 14 resistance R 14 are the output V of this module _dm.The 13 resistance R 13 and the 14 resistance R 14 are 1kOhm.

2.5 filtration module

Please refer to Figure 11, filtration module adopts MAX4101ESA (U5) to realize.

The input end V of demodulation module _dmpin two (input of U5 is negative) by the 15 resistance R 15 and U5 is connected; Input end V _dmby the 7th capacitor C 7, with ground, be connected, the 15 resistance R 15 is 1kOhm, and the capacitance of C7 is 1nF; The rear ground connection of pin 3 series connection the 16 resistance R 16 of U5, the 16 resistance R 16 is 1kOhm; The pin 6 of U5 is connected to pin two by the parallel circuit of the 8th capacitor C 8 and the 17 resistance R 17, and the capacitance of the 8th capacitor C 8 is 4.7nF, and the 17 resistance R 17 is 200kOhm; The pin 7 of U5 meets the positive VCC of power supply; The pin 4 of U5 meets power-VSS; The output signal that the pin 6 of U5 is this module, be the signal output part V of chopper amplification circuit _out; Other modules, as supply module, provide the voltages such as VCC, VSS, VL for the chopper amplification circuit, adopt the power supply of conventional power supply +/-5V to realize; The CLK signal adopts the conventional clock signal to realize, repetition frequency is 3.5kHz, and amplitude is +/-5V, at this, no longer repeats.

3, signal compensation module

This signal compensation module, compensate according to following formula for the signal to the output of chopper amplification circuit, thereby reduce, even offsets the crosstalk response between three-axis sensor.

By this signal compensation module, the magnitude of voltage of sensor output is:

${V^{\&prime;}}_x=\frac{1}{(a-1)(2a-1)}[(1+a+2\mathrm{ab}{P}_x/S_x)V_x-\frac{a+b{P}_y/S_y}{P_y/P_x}{V}_y-\frac{a+b{P}_z/S_z}{P_z/P_x}{V}_z]$

${V^{\&prime;}}_y=\frac{1}{(a-1)(2a-1)}[(1+a+2\mathrm{ab}{P}_y/S_y)V_y-\frac{a+b{P}_x/S_x}{P_x/P_y}{V}_y-\frac{a+b{P}_z/S_z}{P_z/P_y}{V}_z]$

${V^{\&prime;}}_z=\frac{1}{(a-1)(2a-1)}[(1+a+2\mathrm{ab}{P}_z/S_z)V_z-\frac{a+b{P}_x/S_x}{P_x/P_y}{V}_x-\frac{a+b{P}_y/S_y}{P_y/P_x}{V}_y]$

Wherein, parameter a is induced field lateral cross talk ratio, and parameter b is coil current magnetic field lateral cross talk ratio, P _x, P _y, P _zfor induced field frequency response, S _x, S _y, S _zfor the response of coil current field frequency, V _x, V _y, V _zfor the sensor output voltage value by before the signal compensation module.

Below introduce the principle of this signal compensation module: at first utilize the Helmholtz coils of three pairs of quadratures, produce trivector uniform magnetic field space, utilize jig, fixedly three direction of principal axis of triaxial magnetic field sensor are parallel with three directions of Helmholtz coils.Suppose that three-axis sensor is in full accord, absolute symmetry, only need to take wherein an axle measured value as with reference to getting final product.Here, take the Z direction as the example explanation:

At first, allow the Helmholtz coils of Z direction produce uniform magnetic field, triaxial magnetic field sensor is under the excitation in this magnetic field, X, Y, tri-directions of Z all have output, wherein the Z durection component is principal component, X, the magnetic field sensor of Y-direction is output as crosstalk signal, is component of degree n n, the ratio of component of degree n n and principal component is designated as to induced field lateral cross talk ratio a, strictly, this induced field lateral cross talk ratio a is under the effect excitation in a direction magnetic field, with it the magnetic-field component of arbitrary cross stream component output of quadrature and the ratio between excitation components;

Secondly, give the Z direction sensor by a certain size electric current, measure the magnetic field of this electric current generation at x, the output that Y direction causes, this ratio is b, strictly, described coil current magnetic field lateral cross talk ratio b is a direction coil under the effect excitation of certain electric current, with it the current component of arbitrary cross stream component output of quadrature and the ratio between excitation components.

After obtaining the measured value of crosstalking, can adopt following algorithm to compensate.

Suppose to be parallel to x, y, the externally-applied magnetic field of z direction is respectively Φ _xp, Φ _yp, Φ _zp, without the voltage that in the situation of crosstalking, three-axis sensor is sensed, be respectively: V ' _x, V ' _y, V ' _z, in the situation of crosstalking, magnetic field and voltage that three-axis sensor is sensed are respectively Φ _x, Φ _y, Φ _z, V _x, V _y, V _z, the induced field that the electric current passed through in coil produces is respectively Φ _xs, Φ _ys, Φ _zs, can obtain following magnetic field equation:

Φ _x=Φ′ _xp+a(Φ′ _yp+Φ′ _zp)+b(Φ′ _ys+Φ′ _zs)

Φ _y=Φ′ _yp+a(Φ′ _xp+Φ′ _zp)+b(Φ′ _xs+Φ′ _zs) (12)

Φ _z=Φ′ _zp+a(Φ′ _yp+Φ′ _xp)+b(Φ′ _ys+Φ′ _xs)

Bring frequency response P into _x, P _y, P _z, S _x, S _y, S _z, without the voltage that in the situation of crosstalking, three-axis sensor is sensed, be respectively: V ' _x, V ' _y, V ' _z, in the situation of crosstalking, the voltage that three-axis sensor is sensed is respectively V _x, V _y, V _z, can obtain following voltage equation:

$\begin{array}{c}{V}_x={V^{\&prime;}}_x+a(\frac{{V^{\&prime;}}_y}{P_y}+\frac{{V^{\&prime;}}_z}{P_z})P_x+b(\frac{V_y}{S_y}+\frac{V_z}{S_z})P_x\\ V_y={V^{\&prime;}}_y+a(\frac{{V^{\&prime;}}_x}{P_x}+\frac{{V^{\&prime;}}_z}{P_z})P_y+b(\frac{V_x}{S_x}+\frac{V_z}{S_z})P_y\\ V_z={V^{\&prime;}}_z+a(\frac{{V^{\&prime;}}_y}{P_y}+\frac{{V^{\&prime;}}_x}{P_x})P_z+b(\frac{V_y}{S_y}+\frac{V_x}{S_x})P_z\end{array}---\left(13\right)$

Simultaneous solution system of equations (13) can obtain:

$\begin{array}{c}{V^{\&prime;}}_x=\frac{1}{(a-1)(2a-1)}[(1+a+2\mathrm{ab}{P}_x/S_x)V_x-\frac{a+b{P}_y/S_y}{P_y/P_x}{V}_y-\frac{a+b{P}_z/S_z}{P_z/P_x}{V}_z]\\ {V^{\&prime;}}_y=\frac{1}{(a-1)(2a-1)}[(1+a+2\mathrm{ab}{P}_y/S_y)V_y-\frac{a+b{P}_x/S_x}{P_x/P_y}{V}_y-\frac{a+b{P}_z/S_z}{P_z/P_y}{V}_z]\\ {V^{\&prime;}}_z=\frac{1}{(a-1)(2a-1)}[(1+a+2\mathrm{ab}{P}_z/S_z)V_z-\frac{a+b{P}_x/S_x}{P_x/P_y}{V}_x-\frac{a+b{P}_y/S_y}{P_y/P_x}{V}_y]\end{array}---\left(14\right)$

The above-mentioned system of solutions is the magnetic sensor backoff algorithm, parameter a wherein, b, P _x, P _y, P _z, S _x, S _y, S _zall by and only by sensor itself, determined, can be obtained by apparatus measures, with external magnetic field, do not change.Add backoff algorithm in final output, utilize this method measurements and calculations, can make crosstalking between three axles significantly reduce, effectively improve the accuracy of observation of three-axle magnetic field.

It should be noted that, the induction type triaxial magnetic field sensor with signal compensation module is a preferred embodiment of the present invention, and the signal of its output can react real magnetic field situation more accurately.In other embodiments of the invention, this signal compensation module also can be omitted, and does not affect equally the invention process.

The present embodiment induction type triaxial magnetic field sensor, length is reduced into 0.2m-0.3m, and the range of decrease is about 75%; Weight is less than 6kg, and the range of decrease is about 25%, can be integrated in a hydrospace detection sealed ball float, and length and weight will be much smaller than existing commercial products.The schematic diagram that Figure 12 is embodiment of the present invention induction type triaxial magnetic field sensor frequency response measurement method.The technical indicator of the existing induction type triaxial magnetic field sensor that as shown in Figure 2, the technical indicator of the present embodiment induction type triaxial magnetic field sensor and length are 1.0m-1.4m is suitable.

So far, by reference to the accompanying drawings the present embodiment be have been described in detail.According to above description, those skilled in the art should have clearly understanding to induction type triaxial magnetic field sensor of the present invention.

In addition, the above-mentioned definition to each element and method is not limited in various concrete structures, shape or the mode of mentioning in embodiment, and those of ordinary skill in the art can replace simply to it with knowing, for example:

(1) FERRITE CORE can also substitute with other soft magnetic materials;

(2) the electric current amplification module can also be substituted by the negative feedback module.

In sum, sensor body of the present invention and the induction type triaxial magnetic field sensor of applying it are assembled magnetic flux by add disk at original slender type magnetic core two ends, the equivalence raising the length-diameter ratio of magnetic core, broken through the noise margin of traditional induction type triaxial magnetic field sensor in the finite space, and utilize experiment measuring and algorithm compensation to make three axis signal crosstalk signal minimums, length and weight will be much smaller than existing commercial products, reduce volume, weight and the cost of ocean EM exploration instrument, realized the miniaturization of induction type triaxial magnetic field sensor.

Above-described specific embodiment; purpose of the present invention, technical scheme and beneficial effect are further described; institute is understood that; the foregoing is only specific embodiments of the invention; be not limited to the present invention; within the spirit and principles in the present invention all, any modification of making, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.

Claims (13)

1. a sensor body, is characterized in that, comprising:

Core structure, longitudinal profile is I shape, and center section is slender rod shaped magnetic core, and two end portions is flat focus magnetic flux device;

Inductive coil, uniform winding is in the periphery of described core structure center section.

2. sensor body according to claim 1, is characterized in that, in described core structure: described center section is elongated cylindrical; It is flat cylindric that described two end portions is.

3. sensor body according to claim 2, it is characterized in that, in described core structure, the ratio of focus magnetic flux device diameter and center section diameter is between 2:1～10:1, and the ratio of magnetic flux collector length and center section length is between 1:1～1:5.

4. according to the described sensor body of any one in claims 1 to 3, it is characterized in that, also comprise:

Skeleton, be arranged at the periphery of the described center section of core structure and the inboard of described two side portions, and described inductive coil is wound on the skeleton of core structure center section periphery.

5. according to the described sensor body of any one in claims 1 to 3, it is characterized in that, the material of described core structure is soft magnetic ferrite.

6. an induction type triaxial magnetic field sensor, is characterized in that, comprising:

The sensor body module, comprise detection direction three sensor body as claimed in claim 1 perpendicular to each other;

Three groups of chopper amplification circuit, carry out the amplitude enhancing to the signal of three sensor body inductive coil outputs by chopping way respectively.

7. induction type triaxial magnetic field sensor according to claim 6, is characterized in that,

The matching network module, for inductive coil export resonance point is compensated, eliminate resonance spikes, level and smooth tuning-points place's impedance;

Modulation module is modulated to high frequency for the square-wave signal that adopts predeterminated frequency by the signal of matching network module output, thus the chopping signal of realization;

The electric current amplification module, adopt operational amplifier or the pipe amplifier carried out to the low-noise current amplification to the chopping signal of modulation module output;

Demodulation module, adopt and the on all four circuit structure of modulation, and the useful signal in electric current amplification module output signal is demodulated to low frequency, thereby in the electric current amplification module, operational amplifier or 1/f noise that the pipe amplifier is introduced are modulated onto high frequency; And

Filtration module, the high-frequency signal that modulation /demodulation is brought filters, and retains useful signal.

8. induction type triaxial magnetic field sensor according to claim 7, is characterized in that, in described matching network module: from the induced signal of inductive coil output, pass through the first resistance (R1) series connection ground connection; And the induced signal of this inductive coil output after the parallel circuit of the second resistance (R2) and the first inductance (L1) as the output V of matching network module _in.

9. induction type triaxial magnetic field sensor according to claim 7 is characterized in that:

Described modulation module adopts cmos analog switch chip ADG413 (U1) to realize, its each pin arranges as follows: pin one, pin 8, pin 9, pin one 6 connect clock signal clk; The positive signal V of pin 3 and pin one 1 matching connection mixed-media network modules mixed-media output _in; Pin 6, pin one 4 connect signal ground; Pin two, pin one 5 are just being exported for signal, and pin 7, pin one are born for signal output for No. 0, connect respectively the input end V of amplification module _m1and V _m2; Pin one 2 connects logic voltage value VL; Pin one 3 connects the positive voltage VCC of power supply;

Described demodulation module and modulation module symmetry, adopt ADG413 (U4) to realize, its each pin arranges as follows: pin 3 and 14 accesses respectively the signal V from amplification module _ma1with signal V _ma2; Pin one and pin one 6 connect the CLK signal simultaneously; Pin 4 connects power-VSS signal; Pin 5 connects the GND signal; Pin one 2 meets VL; Pin one 3 meets the positive VCC of power supply; Pin two and pin one 5 short circuit after the 13 resistance (R13) and the 14 resistance (R14) of connecting respectively is the output V of this demodulation module _dm.

10. induction type triaxial magnetic field sensor according to claim 7, is characterized in that, the output V of described demodulation module _dmby the 7th electric capacity (C7) ground connection; Described filtration module adopts MAX4101ESA (U5) to realize, its each pin arranges as follows:

Pin 3 is as just inputting, by the 16 resistance (R16) ground connection;

Pin two is negative as input, is connected to the output V of described demodulation module by the 15 resistance (R15) _dm;

Pin 6 is connected to pin two by the parallel circuit of the 8th electric capacity (C8) and the 17 resistance (R17);

Pin 7 meets the positive VCC of power supply;

Pin 4 meets power-VSS;

The output signal that pin 6 is this demodulation module, be the signal output part V of chopper amplification circuit _out.

11. induction type triaxial magnetic field sensor according to claim 7, is characterized in that, described amplification module is divided into first, second and third grade of series connection amplifying circuit;

First order amplifier section is comprised of pipe-pair of pipes (Q1) and second pair of pipe (Q2) FET; Wherein: the G utmost point of pair of pipes (Q1), second pair of pipe (Q2) is connected to respectively the output V of modulation module _m1and V _m2; S utmost point short circuit, its common port is connected to power supply negative voltage VSS through current source 11; The D utmost point is connected to power supply positive voltage VCC by the 3rd resistance (R3), the 4th resistance (R4) respectively, and wherein, the D utmost point of Q1, Q2 is respectively as the output terminal of first order amplifying circuit.

Second level amplifying circuit adopts MAX4101ESA (U2) to realize, its each pin arranges as follows: pin two is connected to the D level of second pair of pipe (Q2) in first order amplifying circuit successively through the 5th resistance (R5) and the first electric capacity (C1); Pin 3 is connected to the D utmost point of first order amplifying circuit (Q1) successively by the 6th resistance (R6) and the second electric capacity (C2); Pin 6 is connected with pin two with the 8th resistance (R8) shunt circuit through the 4th electric capacity (C4); Pin 3 is connected with ground with the parallel circuit of the 3rd electric capacity (C3) through the 7th resistance (R7); Pin 6 is connected with Vm1 by the 20 resistance (R20), the 18 resistance (R18) series connection, adopts between the 18 resistance (R18) and the 20 resistance (R20) with the 19 resistance (R19) and is connected in series on the ground; Pin 4 connects power-VSS; Pin 7 connects the positive VCC of power supply; Pin 6 is as the output terminal of second level amplifying circuit; Pin 6 is connected with Vma2 by the 5th electric capacity (C5), and Vma2 is connected with ground by the 12 resistance (R12);

Third level amplification also adopts MAX4101ESA (U3) to realize, its each pin arranges as follows: pin two, as the input negative terminal, is connected to pin 6 in the amplifying circuit of the second level through the 9th resistance (R9) successively; Pin two is as the input positive ending grounding; Between pin two and pin 6, adopt the tenth resistance (R10) to realize series loop; Pin 4 connects power-VSS; Pin 7 connects the positive VCC of power supply; Pin 6 is connected to output terminal V by the 6th electric capacity (C6) _ma1, V _ma1by the 11 resistance (R11), with ground, be connected; V _ma1and V _ma2input end as third level amplifying circuit.

12. according to the described induction type triaxial magnetic field sensor of any one in claim 6 to 10, it is characterized in that, also comprise:

The signal compensation module, for the signal to the output of chopper amplification circuit compensates according to following formula, to reduce, even offset the crosstalk response between three-axis sensor:

${V^{\&prime;}}_x=\frac{1}{(a-1)(2a-1)}[(1+a+2\mathrm{ab}{P}_x/S_x)V_x-\frac{a+b{P}_y/S_y}{P_y/P_x}{V}_y-\frac{a+b{P}_z/S_z}{P_z/P_x}{V}_z]$

${V^{\&prime;}}_y=\frac{1}{(a-1)(2a-1)}[(1+a+2\mathrm{ab}{P}_y/S_y)V_y-\frac{a+b{P}_x/S_x}{P_x/P_y}{V}_y-\frac{a+b{P}_z/S_z}{P_z/P_y}{V}_z]$

${V^{\&prime;}}_z=\frac{1}{(a-1)(2a-1)}[(1+a+2\mathrm{ab}{P}_z/S_z)V_z-\frac{a+b{P}_x/S_x}{P_x/P_y}{V}_x-\frac{a+b{P}_y/S_y}{P_y/P_x}{V}_y]$

Wherein, parameter a is induced field lateral cross talk ratio, and parameter b is coil current magnetic field lateral cross talk ratio, P _x, P _y, P _zfor induced field frequency response, S _x, S _y, S _zfor the response of coil current field frequency, V _x, V _y, V _zfor the sensor output voltage value by before the signal compensation module.

13. induction type triaxial magnetic field sensor according to claim 12 is characterized in that:

The value of described a is between 0-5%; The value of described b is between 0-10%.

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